: The overall goal of this investigation is to determine the mechanisms of action of IL-1 in brain injury following ischemia or reperfusion. The parameters of brain injury to be monitored include edema, cerebral infarction volume, cerebral blood flow, blood brain barrier permeability, and changes in pathology using methods of immunohistochemistry and enzyme assays. Signs of inflammation to be assessed include the activation of microglial cells and recruitment of neutrophils; in addition, levels of relevant cytokines and adherence molecules are to be monitored. Finally, Adenovirus-IL-1ra constructs are to be used to over-express IL-1ra in the brain to inhibit IL-1-mediated effects in an attempt to establish relationships between IL-1 production and the stimulation of activities that may be responsible for the tissue damage observed in these models of brain injury. Thus, the Specific Aims of the proposal are: Specific Aim 1: Identify the mechanism by which IL-1 contributes to brain injury during permanent middle cerebral artery occlusion (pMCAO). Studies performed to satisfy this aim are to include determinations of 1) the time course and location of IL-1 in the ischemic mouse brain, 2) the relationship between the release of IL-1 and other cytokines (e.g., IL-2, IL-6, IL-8, TNFalpha), 3) the role of IL-1 in induction of cell adhesion molecules (e.g., ICAM-1 and CD62E) and infiltration of circulating inflammatory cells (i.e., myeloperoxidase+ neutrophils), and 4) the role of IL-1 in the accumulation and activation of microglial cells. Specific Aim 2: Determine whether IL-1 contributes to brain injury during temporary middle cerebral artery occlusion (tMCAO). Studies performed to satisfy this aim are virtually the same as those presented for Aim 1 except the temporary instead of permanent MCAO is to be performed. Therefore, during reperfusion, determinations to be performed are to include 1) the time course for the expression of IL-1beta in mouse brain following tMCAO, 2) whether transient over-expression of IL-1ra produced following intraventricular delivery of the IL-1ra gene carried by adenovirus vectors decreases reperfusion brain injury, and 3) the role of IL-1 in induction of cell adhesion molecules and infiltration of circulating inflammatory cells.